One more thing - given the option between a balanced or unbalanced version of a given cable, you probably want to use the balanced version. The discrepancy arises because RCA is inherently a single-ended connector (i.e. 2 conductors as opposed to XLR's 3). The potential for the chassis grounds of source and amplifier to float with respect to each other can lead to amplifier hum, for example.

I'm not sure you need to go to the expense of XLR type connectors, unless you have no choice. The differences and benefits between balanced and unbalaced lines can be confusing. Unless you have a balanced system, you won't have a balanced input without some circuitry or at least a balancing transformer. In-home it is not necessary to use a balanced system unless your cable run is 20 or 30 feet.

If your new amp has 1/4" connectors I'd use them, in fact many have 2 per channel and it is very easy to gang connections with a short jumper between the 2 channels. That would be the same as a "Y" connector. Have you tried to look at an online version of your manual to find out the back panel configuration? It may be much easier than you're planning to make it. Search for a manual.

Balancing may not be important in Bob's home theater, but there are other pragmatic reasons for using the XLR connections - maybe more important for PA applications than for use in the home, but still worth mentioning:

1) the XLR engages all of its conductors at once, and can not short circuit the signal lines during connection / disconnection

2) the XLR is a positive locking connector

Just a thought - if the amp has both XLR and 1/4" phone plug inputs, could you achieve the split by using a single RCA to XLR from the receiver to one amp input, and then use a 1/4" phone plug jumper between the two input jacks on the amp?

I know my EXISTING connections are fairly standard, however the LSA900 I have coming in the mail is an unknown. The panel connection picture from the company I purchaced from just blows...can't see well enough to tell.

The 'balanced / unbalanced' thing is a whole new can of worms I didn't know about. Hopefully it won't be an issue.Should find out in a day or two.

It looks like it has 1/4 inch, and XLR inputs. Outputs you have Speakon connectors and binding posts. Which is the normal inputs and outputs for pro audio amps.

If you are going to be running one channel to one speaker you will be putting 225 watts to that speaker at 8 ohms. You could running the amp in Mono/Bridged and get 900 watts at a 4 ohm speaker load by running the speakers in parallel. Just watch your phasing of the speakers.

15" for sure. Total size of the box you'll stare at isn't a big difference. Driver price difference not much. Have you read the entire thread? I got the Dayton Series II's from parts express for $88 each. Think it might be pretty cool.

After reading the post from gildcm, I went to the web site for Legion Sound to find a better pic of the LSA900. Can't find one, maybe THIS is the reason it was $70 off. They don't make it anymore??? They only have the 800, and 1200, no 900.

WAAAYY better guys here can tell you if the 3 10" JL's you already own would be good. Or if you should build the 15" box, install the one B.W. and down the road buy another. This may be a bad idea, but how about a 15" HWK, install the B.W. then later add a Dayton or two. They may not play well together, but just one idea??? BUt I think most would agree 15" would be be better than 10".

As far as the difference in connector / termination, I also like the idea of the XLR. The 1/4" reminds me of the 1/8" stereo plugs that you would here static until you rotate the plug... not what I need.

The 2 Dayton Drivers are in, WOW 15" is big. Arrived in perfect condition.Amp came, but nobody was home to receive it. Will pick up at post office Friday (got the 3 day weekend coming up). Will purchace MDF and misc materials Friday at Home Depot. Screen fabric for 140" diag. front projection is in, will pick up Friday.Berkline Home Theater seating should be in any day now.

Having a hard time focusing on my job recently... May have to call in sick Thursday ;D ..... Na, gotta pay for this stuff somehow.

As far as the difference in connector / termination, I also like the idea of the XLR. The 1/4" reminds me of the 1/8" stereo plugs that you would here static until you rotate the plug... not what I need.

Bob [/quote]

I'm not quite sure where the notion came from that you will be immune to those problems simply by using an XLR connector. Pros using that amp may have to set it up in 4 or 5 different locations every week and put more wear and tear on every connection than you will at home.

There are many reasons to use an XLR, but the reasons stated for not using 1/4" is mainly encountered when using an amatuer grade connector. If your amp has high quality jacks and you buy pro quality plugs, you won't experience any static or degradation in the signal transfer. The shorting of the output can become a concern with certain tube outs, but generally you don't want to hot swap audio gear any way. Develope good habits from the beginning regarding your new amp.

I guess my unfounded problem with "rotateable" type terminations, stems from when I was a kid. Remember the portable FM and cassette radios? Remember having to rotate the connector (and then using scotch tape wrapped around the connector to hold it in place? I suppose in reality, (with pro grade) these terminations are much better than I remember. Of course my walkman didn't use 1/4" either.

When you say develop good habits with my amp, are you refering to hot swapping?

[quote author=Bob link=1137542099/60#69 date=1138194607]When you say develop good habits with my amp, are you refering to hot swapping?

Bob [/quote]Yep!I watched as a friend once tried switching stuff around and before I could stop him, the speaker outs from 2 different amps touched [LIGHTNING] and it fried both his new amps. He was not practicing "Safety First" as they say.

[quote author=Bob link=1137542099/60#71 date=1138198356] :o :o Not a happy camper......Thanks, that is a practice I should start. I've been known to yank S-video, and component cables while equipment was on. BAAAD!! Stop it....

Bob [/quote]I don't know much about the mechanics of video, but I know many of the circuits are assembled in static free clean rooms because some of the chips used in that gear have microscopic conductors that are sensitive even to static electrical discharge that we couldn't feel. I'm sure the supporting circuitry helps to protect it to some degree, but I prefer not to temp or dare The Devil.

How true. I put in a good quality DVD, and was switching from composite, to S-video, to component just to see how much of a difference was visible. I thought (apparently not ::) ) that If I made the changes fast enough it would be easier to see the differences as opposed to shutting everything down, swapping cables, firing all back up, and finding the same refence point on the DVD. I wanted to do it fast so my mind would'nt "forget" what it looked like. Good idea in theory, but in practice I was 'daring the devil' as you say.

Yes, by the way, there is a big difference. But we all knew that anyway.

Bob (willing to sacrifice my equipment for the better of the community)

Quick question, in a dual driver HWK, I'm thinking about mounting the top driver face up (magnet down in center chamber). Do I set driver in hole from the top chamber, resting it on the back side of the driver flange with gasket. Or, do I install in center chamber FROM the center chamber, so the built in gasket is against the bottom of the top divider.

Or does it matter.

Reason is, ease if installation, holding the driver with one hand trying to install fasteners with other hand. Easier to just set it in hole.

I guess it depends on how you built it. I've seen some pics where the whole side was removable, others had a removable panel in the center chamber, and some made both ends removable. My next one I plan to make one side removable to make access to everything easier.

I've only built one and the ends were removable and I simply dropped the drivers in from the top and bottom. I used black sticky drain pipe putty as a gasket, which is available at Home Depot - a few bucks for a huge roll. It makes a fairly permanent installation, but you can pry the driver lose if you need to. A similar product that is white and made for windows is also good. BTW I had the baffles loaded with "T" Nuts before I glued them in place.

Not a bad idea about the putty. In the automotive industry we use a material we call 'dum dum'. It's about 1/4" - 3/8" diameter 'rope' that comes in a roll. Black and gooey used to seal HVAC in cars. I think our parts department has some. ???

I'm thinking I'll make one entire side removeable to ease in driver musical chairs. Will probably design some overbuilt PITA as a gasket. Thought about a 48" piano hinge to make almost a closet door type setup. You've seen the pins racecars have to hold the hoods on, that would be the latch. Would require extensive gasketing, almost like a refrigerator. Somehow keep gasket in place during use. No, .... I won't call fridgedaire and ask the spl rating of the fridge gasket. ::)

I'll bet "dum-dum" is the same stuff the plumbers use. Since you are in the auto industry and want a bad news gasket ..... think about what they use for pick up toppers as a gasket. It has glue on one side, too.

I would forget the door idea and stick to lids top and bottom. This cabinet needs to be as stiff as possible, and I can't really see an advantage of having a hinged door on something which is likely not to be opened with any sort of frequency. Drivers mount to the upper face of the top baffle and the lower face of the bottom baffle, through the ends. I used T-nuts for this.

Of course, Sean is right, but I was thinking we had gone past reality and were engaged in thought play at this point. At least that's what I got from your hinge idea.

If you're worried that it will take a long time to decide which "tuning" you prefer, don't. You have 2 drivers, right? You also have 2 ports and 2 chambers, the center one doesn't make sound so it doesn't count.

Placing them with the magnets in the center chamber will give you the lowest tuning in both ports.

Placing them with the magnets in the vented chambers will give you the highest tuning in both ports

Both of those arrangements will give you a push-pull loading with the drivers firing in opposite directions and result in the least non-linearity distortion. Either way I would wire them electrically out of phase with each other so that they work in unison...... both helping each other.

You can also place the drivers with both magnets down, push-pull. This will give you the lowest tuning on the low port and the highest tuning on the high port. In other words the widest bandwidth box.

Reversing them and placing both magnets up gives you the narrowest bandwidth.

Ok, Ok, I got a little crazy there, sorry. One of my faults is that I'll over analyze something to death. Can't even build a freakin' box without over-engineering. Should have been born a Porsche, or BMW engineer.

Seal all four sides so the center chamber will never be accessible. Mount the drivers in the ends, Leave end caps removable, and do any moving around from the ends.

Yes DD, I do have 2 drivers. Thinking the magnets will both end up in center chamber. My (6) surrounds have a range from 65hz to 21khz (Niles OS-10's). All currently set to large since no sub yet. So I havn't played with built in crossover settings on the receiver much (Harman Kardon AVR 525). They don't have much 'punch' left that low in hz, so some tweeking will be needed with crossover setting, and driver placement. Will purchace some form of calibration device to assist. Still havn't done anything with room acustics so will have to recalibrate once that's done. Slow process. Money, time, and knowledge making it that way. Mainly money.....

Bob

For some reason I can only post at work. At home this web site will let me log in, and acknowledge me at the top of the screen. If I click on anything it will direct me there, but top of screen says I'm a guest again. Will NOT keep me logged in. Hmmm. So no posts this weekend.

I will try to have pics on Monday morning pending development of photos.

Yea, using windows, havn't tried deleting cookies. I did lower my security settings to allow all cookies (Hello virus, come on in) that made no difference. Having no problem at work, only home. Totally unable to post at home. Fairly annoying. Actually have more internet time at work then at home. If I'm at home I'm building / tweeking / destroying something. Work is in slow season, and boss is very tolorant of play time ;D.

if you decide tyo keep the magnets in center chamber, hot glueing a dowel of correct lengths to the rear of each driver will keep the baskets coupled even more. This makes a huge effect in dipole full range cabnets I have done. Perhaps it would benefit a HWK.

I used to cram/jam/brace the magnets in my folded horns against the backs of the cabinets and it cleaned up lots of harmonic mishappenings. Making the entire supporting mass one unit really helped in such a high pressure area. Any time you make a cabinet more solid it is a good thing.

That funny hole is necessary for cooling the voice coil. Don't block it! You could still have the same bracing by using a flat board with a "U" shape cut out of the ends. Make the U bigger than the hole and it won't impede the airflow.

"Isobaric" refers to pressure or more precisely, equal pressure. When you put 2 drivers together and make them work as one, the pressure between them remains equal on one side of the motor and aided by the other motor and cone, gain a little bit a stability from the "loading". Two motors working as one, coupled with an equal(izing) pressure chamber in between is stronger than one motor.

Many people will say it's a waste of a good driver and that one driver alone will be just as good. They would be correct as far as the first half, or so, of the drivers operating capability goes.

It's when you really need to lean on the drivers that the benefit from iso-loading becomes apparent. When really pushed, the double motors are more stable and resist over-excursion better than one single driver alone can.

In addition to all that, when you have them facing each other and they work as one unit, any non-linear distortion will be averaged and theoretically reduced to one half. Non-linearity is caused from a driver moving in one direction with a different compliance, or restance to movement, than it moves in the other direction. If it moves out easier than it moves in, or vice versa, you have a problem ...... a very common problem.

[quote author=DirtDawg link=1137542099/75#88 date=1138320666] any non-linear distortion will be averaged and theoretically reduced to one half. Non-linearity is caused from a driver moving in one direction with a different compliance, or restance to movement, than it moves in the other direction. If it moves out easier than it moves in, or vice versa, you have a problem ...... a very common problem. [/quote]

interesting, i have wondered when people talk about inverting subs, it seems to me the front of a woofer would move more air than the back? people have argued and said it doesnt make a difference, but i cant get my head around the different shape reacting differently with air? flat subs would seem to overcome any differences eh?

Obviously the volume change ahead of the woofer must be equal to the volume change behind it, so from that perspective there is no difference between mounting a woofer magnet in or magnet out; however, compliance differences will occur as a result of the cone surround and spider geometry. For example, a rubber surround which is a half-circle cross section will not deform the same way when the cone moves out versus in - the non linearities are slight in a well designed driver, but for a matched pair of drivers, isobaric mounting averages the non-linearities in each direction so the effective compliance is the same regardless of the direction of cone movement. Where mounting direction matters is when using drivers as direct radiators, as opposed to in bandpass or horn loaded enclosures, since the shape of the driver cone affects how the sound disperses, and having a metal basket and motor assembly right in front of your driver is obviously going to be detrimental from that perspective.

Hwk is finished except for cosmetics. Will have pictures once I get the rest of the pictures on the roll taken.

Things I noticed this weekend:

#1 Legion LSA-900 is a professional piece of equipment. NOT for use in an exposed rack system in a home theater setting. It's LOUD, the two fans in the rear run all of the time. The exhaust is through the grill on the front that runs the entire width of the face of the unit. It's as loud as my microwave. One other minor issue, the blue power indicator LED on the amp projects a perfect beam of high intensity blue light, right into my eyes from 10' away. Almost like it was done on purpose.

#2 My God it's huge. The HWk with 2 15" Dayton's sounds very good. However, I would have thought, with the wattage I have, you would have 'felt' the LFE. This is not to say that the unit hasn't shown me the resonant frequency of various things around my room, along with my wifes tolorance level. But you don't get the "punch in the chest" I was hoping for. Quality of sound is excellent. Needs more tweaking with settings though. Did I mention it's huge? ..... and heavy.

After $450, I'm relatively happy. I thought it would be, .... well ...... more. Especially considering the size of the enclosure, size of drivers, ect.. I don't believe the fine tuning will result in the effect I had hoped, may be I hoped for too much. I'll play after work this week, but will lock myself back in the cave this weekend. Maybe a revelation will strike me as to what I've screwed up.

i also noticed the quality of the bass the hwk produces was much better than i thought it would be. you might find you get more of the 'car audio' bass in your chest effect with 'different placement' i suppose your level of happiness will be dependant on what you prefer, 'bass in chest' or lots of 'quality bass in room', if you find your un happy with the hwk in a few weeks just buy a good 10 in sub and strap it too your chest dureing playback! seriously try the hwk in different locations in the room. and that amp of yours would drive me nuts! as loud as a microwave? its gotta go back.

But you don't get the "punch in the chest" I was hoping for. Quality of sound is excellent. Needs more tweaking with settings though. Bob

p.s. Have I said how big it is? [/quote]

You built a subwoofer that wears make-up?

Hi, Bob,

Punch in the chest is not really bass, and LFE is not really about punch. I may have misguided you if you want "punch". I recommended to place your drivers in the lowest tuning, which would take away some punch and give you more gut disruptive pressure effects. All that stuff moving around and rattling is a sign that something is happening that's powerful.

Before you go too far tuning I would live with it for a few days and get used to what it does with many different programs and goof with the placement a little.

You will find that moving the cabinet will have quite an effect on the output, even turning it in the same spot can change everything. After getting tired of moving it around, you can try changing the way the drivers mount inside to re-tune it to a (higher if you want more punch) range you like better.

Another point to take into account before you do any tuning at all is that the drivers need to break-in a little. So, for your new drivers I suggest you just play them for a few days and see what happens, then change stuff, one thing at a time, to improve your experience.

As far as your amp goes, chech to see if there is a "speed" switch on the fans. That light is designed to be OBVIOUS in a smoky room up to 100' or more away. You can always put tape over it. I like to use some of that make-up you mentioned earlier. After I'm satisfied I won't need warranty service I use nail polish to hide those annoying lights, but don't tell anyone.

DirtDawg, what I'm going for is a rosy blush effect, how much Cover Girl foundation will it take to cover the enclosure? Will it need 2 coats?

Yea, I'll play this week at night after work. Won't make any major adjustments. May install wheels on the damn thing so I can move it around.

I sold my sectional to make way for the new stuff that should be here any day now. Realize this will impact acustics. That's another reason I'm not getting too anal about fine tuning, the lack of a big cushy bass trap I can sit on...... Will place it behind the seating position to hear what that's like, but it's futile to do that now.

I've heard of people playing sweeps for 2-3 days to break-in new drivers, what do you think?

As far as output, I work with 'one of those' car audio guys :) he's got several cd's with tones and sweeps. Things rattle in the room when there is very little volume. Which seems like a good thing (not the rattling of course) but not quite the intensity I thought this monster would create. Are you saying it's a trade off between VERY low hz, and the 'feeling' I'm wanting?

[quote author=Bob link=1137542099/90#95 date=1138635679]. Are you saying it's a trade off between VERY low hz, and the 'feeling' I'm wanting?

Bob [/quote]

no :-X, its the difference between what it 'should' sound like and what it 'does' sound like. a dinosaur takeing a step 100 feet away would have a very distinct sound, as does a hammond organ and a fender precision bass.the idea is to set up our rigs, so they reproduce "faithfully" the origional sound.trouble is with so many subwoofers is that you would not be able to tell what kind of instrument it was, or exactly how heavy the creature is, because EVERYTHING SOUNDS EXACTLY THE PHUKING THE SAME. its very exciteing to have a sub that will make it obvious when your listening to a bass guitar or human hands drumming on a table ;D set all your gains to FLAT. put on a very familiar disk (music) play at medium levels and adjust sub amp until it feels / sounds good in the main listening seat.no bass boost, no loudness, no eq no nada, just a clean signal amplified well and into the hwk! when set up like this the onlything you should ever have to adjust is the 'level or volume' of the sub. if something your playing sounds dryer or sloppyer or harder or deeper its because its 'recorded' that way, and the fact that you can hear the difference is a good thing

Like 60 has pointed out you don't have to trade one for the other. But to try to explain what we are both talking about, you may have heard many subs that couldn't do anything except punch you in the chest. That goes for way over half of the subs out there. Even the ones that can get low many times have such an exagerrated upper bass that they just sound punchy.

Generally the "punch" frequencies are in the upper part of the bass, like 60Hz to 100 Hz. They have a hard sound no matter what causes them. The lower 40Hz and below range has a softer feel to it. Just as strong and powerful to the body, but very different sounding. They are both part of the sound you want to hear, but you shouldn't think of one being better than the other. The perfect sub will play all of it's frequencies at the same level.

The idea of using a familiar CD to set it up is probably the best way. Forget test tones until you are more familiar with what they can do, scientifically, for you. You need some other test equipment to make use of test tones anyway. Once you get it all set up right, though test tones can be a blast.

You don't need to do anything nutty to break in the drivers. Just use them for a few days and they will be mostly there.

60, DirtDawg, I respect that very much. My goal is quality, always has been. I'll never change that. Nothing better than to sit in a perfectly quiet room listening to well recorded music on a decent system. A religious experience all in itself. But, the main goal of this system (95%) is for home theater. So when that dinosaur takes a step, I want to feel it too. I mean a nice solid rumble in my chair. When that rocket takes off or the volcano blows, I want more rumble. But occasionally in a movie sound track, it may be necessary to have even more.

Here's what been in the back of my mind, almost since I started building this room. I was in the listening room at Ultimate Electronics watching a demo of a front projection setup. I started paying more attention to the sub, because you could feel it (in a tactful way) when it was necessary to feel it. After watching for awhile, I got up and looked at the price, $1600.00. Not on my budget for a sub. So I started down the DIY road. I figured I was half way there, I've got woodworking skills, just don't know crap about how to turn a bare driver into a religious experience, ...... an art form.

DirtDawg, refering back to your signature, I would replace 'music' with 'movie'. It's an escape from reality, a drug.

As far as the test tones go, No, I wasn't listening to them pretending to know what I was doing. My point was to listen to some audio tracks that had a LOT a bass. These are tracks that the car audio guys use during competition. All spl's and db's. Not my listening preference. Just playing with my new toy.... Some of the disks had tones too, so I was more, "playing" with them, than anything else.